1. Field of Invention
This invention relates to fabric softening and anti-static compositions and a method of softening fabrics and preventing static electricity from accumulating on said fabrics. More particularly, this invention relates to improved fabric softening compositions in which an anti-static compound has been incorporated, such compositions being particularly adaptable to the treatment of fabrics during the rinse cycle of conventional home washing machines and to the treatment of fabrics with said compositions. In a particular aspect this invention relates to a treating composition which includes a cationic softening agent and an anionic phosphoric acid ester anti-static agent which when applied to synthetic fabrics, including nylon will both soften the fabric and decrease the static electricity to substantially the same degree as cotton.
2. State of the Prior Art
The use of various and diverse chemical materials and particularly cationic quaternary ammonium compounds as softeners for textile products is very well known in the art. It is also well known to employ such materials for their softening effect during the laundering operation and particularly in the rinse cycle of the laundering process. This technique has been necessitated by the fact that the softeners heretofore employed, being mainly cationic in nature, are not compatible with the major type of detergent used in the washing cycle. By far, the predominating type of detergent used in home laundering processes, is anionic in nature and more particularly is of the alkali metal higher-alkyl benzene sulfonate type. To employ a cationic substance, such as the aforementioned softeners, in conjunction with anionic detergent materials, results in a precipitate which is completely ineffective as a fabric softener. This manifestation of incompatibility is also undesirable because it removes detergent from the wash cycle and therefore requires more detergent to accomplish the necessary and desired washing efficiency. As a consequence of these difficulties, it has been absolutely necessary to add the presently available cationic softeners to the clothes in the absence of any anionic detergent and where this is done during washing it must be done during the rinsing cycle.
It is also well known that there is a tendency for laundered articles to yellow when treated with cationic agents. This yellowing of the textiles treated with cationics is believed to be caused by (1) highly colored impurities or by-products in some commercial cationic finishing agents or (2) the presence of high amounts of iron in the finishing agents that may cause staining typical of iron compounds or, (3) due to the presence of alkali when the materials treated with the cationics are ironed or pressed.
A further disadvantage of the cationic fabric softeners is that many of them are waxy or gummy in nature making them difficult to weigh or measure, to mix or disperse with other textile-treating agents, and to place them in a form which may be readily applied to textiles.
There have been several recent developments of anionic softening agents which are substantially compatible with many conventional liquid and/or solid heavy duty detergent compositions and also many of the newly developed softening agents also impart satisfactory anti-static property to many synthetic textile fibers or are compatible with anti-static agents.
U.S. Pat. No. 3,951,826 describes a single phase, all purpose heavy duty liquid detergent composition which contributes softening and anti-static properties to laundry. This aqueous composition uses a mixture of mono- and diphosphate esters of higher alkyl ethoxylates and lower alkyl mono- and diphosphate esters in combination with nonionic detergent and builder. The mixture of ethoxylated phosphate esters is disclosed to impart softening and anionic detergent properties to the composition.
U.S. Pat. No. 3,957,661 describes heavy duty laundry detergent in particulate form having softening properties which combines mono- and di-higher alcohol polyethoxy phosphate ester salts with synthetic anionic organic detergents. It is also suggested that in addition to softening effects the detergent composition imparts an anti-static action during the laundering of synthetic materials.
A detergent-compatible fabric softening and anti-static composition containing molecular smectite clay materials, cationic anti-static agents and acidic compatibilizing agents which permit the simultaneous attainment of fabric softening, static-reduction and cleansing effects of fabrics washed therein is described in U.S. Pat. No. 3,954,632. The smectite clay softeners are anionic as are the conventional cleansing substances in detergent compositions and therefore, as previously described, the cationic anti-static agents are generally ineffective in such compositions. Accordingly, the patentee utilizes compatibilizing agents with substantially water-insoluble quaternary ammonium anti-static agent of the formula [R.sub.1 R.sub.2 R.sub.3 R.sub.4 N].sup.+.sub.n X.sup.n- wherein R.sub.1 and R.sub.2 represent hydrocarbyl groups containing from about 10 to 22 carbon atoms, R.sub.3 and R.sub.4 represent hydrocarbyl groups containing from about 1 to 4 carbon atoms, X is an anion and n is an integer from 1 to 3. It is also suggested in this patent that the quaternary ammonium anti-static agent adds an increment of softening benefits to the fabrics.
U.S. Pat. Nos. 3,862,058, 3,886,075, 3,954,632 and 3,958,059 are directed to fabric treatment compositions which have fabric softening and anti-static properties. The anti-static agents used in these patents comprise a quaternary compound of nitrogen or phosphorous and electrically conductive salts. In U.S. Pat. No. 3,959,155 the anti-static compositions comprising an electrically conductive metal salt dispersed in water-insoluble quaternary compound are employed as detergent-compatible fabric softeners with anionic smectite clay softeners.
U.S. Pat. No. 3,862,045 discloses fabric softening anti-static compositions which include quaternary ammonium salts having two long-chain alkyl groups having 16 to 22 carbon atoms as the softening ingredient and at least one anti-static agent which is an ethoxylated quaternary ammonium compound having the formula [R.sub.1 R.sub.2 (CH.sub.2 CH.sub.2 O).sub.m H(CH.sub.2 CH.sub.2 O).sub.n H].sup.+ X.sup.- wherein R.sub.1 is an alkyl group having 14 to 22 carbon atoms, R.sub.2 stands for an alkyl group having 1 to 3 carbon atoms or a benzyl group, X designates Cl, Br, or C.sub.2 H.sub.5 SO.sub.4, and the sum of m and n is from 5 to 20, or quaternary ammonium compounds expressed by the formula R.sub.3 R.sub.4 R.sub.5 N.sup.+ (CH.sub.2).sub.p COO.sup.- wherein R.sub.3 is an alkyl group having 16 to 22 carbon atoms, R.sub.4 and R.sub.5 stand independently for an alkyl group having 1 to 3 carbon atoms and p is a number of from 1 to 4. These compositions also include nonionic surfactants and at least one additive selected from alcohols, glycols, glycerol, sorbitol and urea. This patent also shows a series of comparative examples wherein phosphate esters were used as anti-static agents but were shown to have undesirable results. In U.S. Pat. No. 3,850,818 the ethoxylated quaternary ammonium salts having the previously given formula are combined with quaternary ammonium salts having the formula R.sub.1 R.sub.2 R.sub.3 R.sub.4 N.sup.+ X.sup.- wherein R.sub.1 and R.sub.2 each represent an alkyl group of 14 to 22 carbon atoms, R.sub.3 and R.sub.4 each represent an alkyl group of 1 to 3 carbon atoms, benzyl or (C.sub.2 H.sub.4 O).sub.n H wherein n is an integer of from 1 to 3 and X represents Cl, Br or C.sub.2 H.sub.5 SO.sub.4, the combination of these two quaternary ammonium salts forming an anti-static softening composition.
In addition to such general formulations, there have also been disclosures of anti-static finishing agents having particular adaptability for synthetic fibers such as polyesters and polyamides. For example, U.S. Pat. No. 2,676,122 discloses that mixtures of amine salts of long-chain alkyl phosphates, whereof the amine portion is an oxy-alkylene amine, such as mono-, di- and triethanol amine, the ethanol derivative of monomethyl and dimethyl amine and morpholine, as described by the following general formula: ##STR1## wherein x designates the numeral 1 or 2 while y is the difference between 3 and x, Alk is a normal alkyl radical having from 8 to 16 carbon atoms, and NX represents an oxyalkylene amine have excellent anti-static effects upon non-cellulosic, hydrophobic textile materials including nylon, polyacrylonitrile, polyethylene terephthalate, etc.
U.S. Pat. No. 3,684,567 describes an anti-static finish for nylon textiles which is durable through laundering. The anti-static finish is applied to the nylon textile fabtic as a solution or solvent dispersion of an ethanolamine of the formula ##STR2## where R is an alkyl radical of 8 to 18 carbon atoms.
U.S. Pat. No. 3,634,117 describes the use of various amine salts of polyethoxyalkyl phosphoric acid esters, N-diamines of quaternary ammonium salts and especially acyl-amino-propyl-dialkyl-ammonium dialkyl phosphates as finishing agents for fibrous or filamentary polyester and polyamide textile materials.
The extensive research and development in this area has led to several commercially fabric softeners which, in addition to their fabric softener qualities, impart satisfactory anti-static effect for most of the synthetic textile fabrics such as polyester fabrics and acrylic fabrics. However, the effectiveness of these fabric softeners have not been entirely satisfactory with regard to their anti-static effect on nylon fibers and the fabrics utilizing such nylon fibers.